| Financial Instruments (Realized And Unrealized Gains (Losses) On Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended | ||
|---|---|---|---|
| Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009 | |
| Realized and unrealized gains on financial instruments, net (note 8) | $ 84 | $ 62 | $ (589) | 
| X | ||||||||||
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- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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